/*-
 * #%L
 * Utility classes for BoneJ1 plugins
 * %%
 * Copyright (C) 2015 - 2023 Michael Doube, BoneJ developers
 * %%
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * #L%
 */


package org.bonej.geometry;

import java.util.Arrays;

public final class Centroid {

	private Centroid() {}

	/**
	 * Find the centroid of an array in double[i][n] format, where i = number of
	 * points and n = number of dimensions
	 *
	 * @param points a set of points in N-dimensions.
	 * @return array containing centroid in N-dimensions
	 */
	static double[] getCentroid(final double[][] points) {
		if (Arrays.stream(points).mapToInt(p -> p.length).distinct().count() != 1) {
			throw new IllegalArgumentException(
				"Points must have the same dimensionality");
		}
		final int nDimensions = points[0].length;
		final double[] centroid = new double[nDimensions];
		for (final double[] point : points) {
			for (int d = 0; d < nDimensions; d++) {
				centroid[d] += point[d];
			}
		}
		for (int i = 0; i < centroid.length; i++) {
			centroid[i] /= points.length;
		}
		return centroid;
	}
}
